CVE-2026-7839CWE-798

UltraVNC repeater ships hardcoded default admin password allowing unauthenticated admin access

Critical · published July 1, 2026

CVSS v3.1
9.1
EPSS
1%
Percentile
50.8
In the wild
Unconfirmed
What it is

UltraVNC repeater through 1.8.2.2 initializes the HTTP administration server with a hardcoded default password. In repeater/webgui/settings.c:197, when settings2.txt is absent on first run the repeater writes the literal string "adminadmi2" as the admin password via strcpy_s(saved_password, 64, "adminadmi2"). The HTTP Basic-auth handler wi_decode_auth() checks this password without rate-limiting or lockout. Any remote attacker who can reach the repeater HTTP port (default TCP 80) can authenticate as administrator using the well-known default credential on a fresh or unmodified installation, gaining full control of the repeater configuration including allow/deny rules and session visibility.

The record
Technical detail
CVSS v3.1
9.1 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00655 · 50.8th percentile
Weakness
CWE-798 · Use of Hard-coded Credentials
Published
2026-07-01T03:33Z
EPSS history
Timeline
  • 01 JUL 03:33Z
    UltraVNC repeater ships hardcoded default admin password allowing unauthenticated admin access
    cvelistv5